# -*-coding:utf-8 -*-
# Author : Mo
# Data : 2022/2/4 9:37
"""
自定义的分页组件,以后如果想要使用这个分页组件，你需要做如下几件事：
在视图函数中
def pretty_list(request):

    # 1.根据自己的情况筛选自己的数据
    queryset = models.PrettyNum.objects.all()

    # 2.实例化分页对象
    page_object = Pagination(request,queryset)

    context = {
        "queryset": page_object.page_queryset,  # 分完页的数据
        "page_string": page_object.html(),      # 生成页码
    }

    return render(request,"pretty_list.html",context)
在HTML页面中：
{% for obj in queryset %}
  {{ obj.xx }}
{% endfor %}
<ul class="pagination">
    {{ page_string }}
</ul>
"""

from django.utils.safestring import mark_safe
from django.http.request import QueryDict
import copy

class Pagination(object):
    def __init__(self,request,queryset,page_size = 10,page_param="page",plus = 5):
        """
        :param request: 请求的对象
        :param queryset: 符合的数据(根据这个数据给他进行分页处理)
        :param page_size: 每页显示多少条数据
        :param page_param: 在URL中传递的获取分页的参数，例如：pretty/list/?page=2
        :param plus: 显示单前页的前或后几页
        """
        query_dict = copy.deepcopy(request.GET)
        query_dict.mutable = True
        self.query_dict = query_dict
        self.page_param = page_param

        page = request.GET.get(page_param, "1")

        if page.isdecimal():
            page = int(page)
        else:
            page = 1
        self.page = page
        self.page_size = page_size

        self.start = (page-1) * page_size
        self.end = page * page_size

        self.page_queryset = queryset[self.start:self.end]

        # 数据总条数
        total_count = queryset.count()
        total_page_count, div = divmod(total_count, page_size)
        if div:
            total_page_count += 1
        self.total_page_count = total_page_count
        self.plus = plus


    def html(self):

        # 计算出  显示单前页前5页、后5页
        if self.total_page_count <= 2 * self.plus + 1:
            # 数据库中的数据比较少，都没有达到11页。
            start_page = 1
            end_page = self.total_page_count
        else:
            # 数据库中的数据比较多 > 11页。

            # 当前页<5时(小极值)
            if self.page <= self.plus:
                start_page = 1
                end_page = 2 * self.plus + 1
            else:
                # 当前页 > 5
                # 当前页+5 > 总页面
                if (self.page + self.plus) > self.total_page_count:
                    start_page = self.total_page_count - 2 * self.plus
                    end_page = self.total_page_count
                else:
                    start_page = self.page - self.plus
                    end_page = self.page + self.plus
        # 页码
        page_str_list = []

        # 首页
        self.query_dict.setlist(self.page_param, [1])
        page_str_list.append('<li><a href="?{}">首页</a></li>'.format(self.query_dict.urlencode()))
        # 上一页
        if self.page > 1:
            self.query_dict.setlist(self.page_param, [self.page - 1])
            prev = '<li><a href="?{}">上一页</a></li>'.format(self.query_dict.urlencode())
        else:
            self.query_dict.setlist(self.page_param, [1])
            prev = '<li><a href="?{}">上一页</a></li>'.format(self.query_dict.urlencode())
        page_str_list.append(prev)

        for i in range(start_page, end_page + 1):
            self.query_dict.setlist(self.page_param, [i])
            if i == self.page:
                ele = '<li class="active"><a href="?page={}">{}</a></li>'.format(self.query_dict.urlencode(), i)
            else:
                ele = '<li><a href="?{}">{}</a></li>'.format(self.query_dict.urlencode(), i)
            page_str_list.append(ele)
        # 下一页
        if self.page < self.total_page_count:
            self.query_dict.setlist(self.page_param, [self.page + 1])
            prev = '<li><a href="?{}">下一页</a></li>'.format(self.query_dict.urlencode())
        else:
            self.query_dict.setlist(self.page_param, [self.total_page_count])
            prev = '<li><a href="?{}">下一页</a></li>'.format(self.query_dict.urlencode())
        page_str_list.append(prev)
        # 尾页
        self.query_dict.setlist(self.page_param, [self.total_page_count])
        page_str_list.append('<li><a href="?{}">尾页</a></li>'.format(self.query_dict.urlencode()))
        search_string = """
                <li>
                    <form style="float: left;margin-left:-1px" method="get">
                          <input name="page"
                                 style="position:relative;float:left;display:inline-block;width:80px;border-radivs:0;"
                                 type="text" class="form-control" placeholder="页码">
                            <button style="border-radivs" class="btn btn-default" type="submit">跳转</button>
                    </form>
                </li>
            """
        page_str_list.append(search_string)
        page_string = mark_safe("".join(page_str_list))
        return page_string
